I know it's not exactly The Second Sex or The Women's Room or any of the other great titles you might expect to find on a feminist's bookshelf, but I love Tolkien's Lord of the Rings trilogy and I'm not ashamed to admit it. Well, OK I am: but only a bit.

And while I may have all the films on extended DVD, and the collector's gift box sets that came complete with the statues of the Argonath and Gollum; and while I may also have my own, almost complete set of collector's models, with display stands, that doesn't make me a nerd. And nor does the fact that I went to the Lord of the Rings exhibition when it came to London's Science Museum back in 2003 (where I came away with a fantastic poster of the Witch King). It just means that I'm a fan. Or something.

Anyway, I don't hold with the theory that LOTR geekdom is an exclusively male preserve. In fact some of the most ardent LOTR fans that I've ever come across have been women. Take my aunt for instance: she reads LOTR from cover to cover every single year, and has been doing so for as long as any of us can remember. Then there's a former colleague of mine, Lucy, whose encyclopaedic knowledge of LOTR, The Hobbit and The Silmarillion is matched only by her equally encyclopaedic knowledge of Star Trek.

I also don't hold with the view that LOTR has nothing to offer women, or that it's about nothing more than, to quote Bidisha: "a club of white men (who) flee (a) a big burning vagina and (b) some black guys in hoods". OK, so it's not the most progressive read you're ever likely to come across, with its all-male fellowship and its dearth of female characters, but it's also not the misogynist tome that some have tried to paint it as.

Granted, most of the women in LOTR are nothing more than background characters, but there are three (four if you count Shelob, but I don't because she's a spider) who have significant roles to play in the plot. There's Arwen for instance, Aragorn's love interest, who defies her father's wishes and renounces her Elven immortality so that she can remain with Aragorn in Middle Earth. Then there's Galadriel, co-ruler of Lothlórien and giver of absolutely spot-on gifts. And last but by no means least, there's Éowyn, niece of King Théoden and heroic slayer of the Witch-King of Angmar, Lord of all the Nazgûl.

For me, Éowyn is up there with all the best kick-ass feminist heroes. She's brave, she's rebellious, and most importantly of all, she's gender non-conformist. In fact, it's her refusal to bow to patriarchal conditioning and accept her designated gender role that ultimately saves the day.

Desperate to be allowed to fight alongside the men, and thwarted from doing so by both Théoden and Aragorn, Éowyn asks: "Shall I always be left behind when the Riders depart, to mind the house while they win renown, and find food and beds when they return?" And when Aragorn asks her what she fears if it's not pain or death, she replies: "A cage. To stay behind bars, until use and old age accept them, and all chance of doing great deeds is gone beyond recall or desire."

Tolkien might not have had much time for women as some have claimed, but in Éowyn he showed that he certainly had some understanding of the frustrations we experience when we're expected to conform to sexist stereotypes.

In the end, of course, Éowyn disguises herself as a man and goes into battle anyway. And its then, when she's face to face with the Witch-King in the Battle of the Pelennor Fields, that we understand she absolutely had to fight, and that the war couldn't have been won without her. "Hinder me? Thou fool. No living man may hinder me!" screams the Witch-King as Éowyn draws her sword. But Éowyn simply laughs at him, and retorts: "But no living man am I! You look upon a woman." And then she pulls off her disguise and kills him.

There's plenty more to be said about Éowyn, about her suicidal tendencies and her ultimate decision to abandon soldiering and become a healer instead, but at the end of the day it's her pivotal role in the plot that matters. Éowyn disproves the myth that The Lord of the Rings is a story that could only appeal to male geeks, and she also disproves the myth that Tolkien was incapable of creating fully rounded female characters.

Obviously Éowyn's not the only reason I love The Lord of the Rings, but when people question how, as a feminist, I can be a LOTR fan, she's definitely my excuse, and I'm sticking with her.

• Thanks to JayReilly who suggested this topic in our birthday open thread.